As you fill in the fields, you will see a preview of the ad to make sure that you've created what you wanted.
If it's ok, click [Save].
Then you will see the list of creatives (in a selected folder). The list displays the status, ID, small Preview, Name of the creative, Type, Size (in pixels), and Wight (in kilobytes).
In order to make changes to the creative, click on its name. You will see the edit page the same as described above.
You can select several creatives via checkboxes on the left, and delete them or make copies: